Kiloparsec-Scale Jets in Nearby Galaxies as Possible Sources of High Energy gamma-ray Emission

Several low-power kiloparsec-scale jets in nearby radio galaxies are known for their synchrotron radiation extending up to optical and X-ray photon energies. Here we comment on the high-energy g-ray emission of such objects, resulting from comptonization of the starlight photon field of the host galaxies by the synchrotron-emitting jet electrons. Particular case of radio galaxy M 87 is analysed in more details, including relativistic bulk velocity of the jet as well as the Klein-Nishina effects. We show, that present upper limits for such an emission imposed by Whipple observations imply that the magnetic field in the brightest knot A of M 87 jet cannot be smaller than the equipartition value. We also comment on the regular (non-active) galaxy NGC 821, for which kpc-scale jet-like feature has been recently discovered in X-rays by Chandra. We conclude, that if the interpretation of this feature as the synchrotron-emitting jet-like outflow is correct, nearby elliptical galaxies can constitute an important class of the extragalactic sources of high energy (from GeV up to TeV) g-ray radiation detectable by the future Cherenkov Telescopes and GLAST